self-selecting

The answer is here, though some of us ‘in the business’ might get a little bit sniffy at the idea of a human sample group that is not only partly self-selecting, but includes people who've paid to be experimental subjects.

Wouldn't you rather have a self-selecting bunch of music industry ‘experts’ censor your music for you rather than have the government do it?

For all our programs, rhetoric and efforts, the university crowd is still a pretty self-selecting one.